Dehydrated potato flakes

ABSTRACT

Dehydrated potato flakes prepared from potato slices, slivers and/or nubbins suitable for use in dough compositions used to make fabricated products. The dehydrated flakes are prepared such that the physical properties in the flake are controlled during processing. The resulting flakes can be used to prepare a more cohesive, non-adhesive, machineable dough.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a Divisional of U.S. patent application Ser. No.09/629,550 filed Jul. 31, 2000 (now U.S. Pat. No. 6,544,580), which is aDivisional of U.S. patent application Ser. No. 09/498,545 filed Feb. 4,2000 (now U.S. Pat. No. 6,312,747), which is a Divisional of U.S. patentapplication Ser. No. 08/886,381 filed Jul. 1, 1997 (now U.S. Pat. No.6,066,353), which claims the benefit of priority to U.S. ProvisionalApplication No. 60/022,521, filed Jul. 1, 1996 and to U.S. ProvisionalApplication No. 60/020,936, filed Jul. 1, 1996, all of which are hereinincorporated by reference.

TECHNICAL FIELD

This invention relates to dehydrated potato flakes and to a method ofpreparing dehydrated potato flakes.

BACKGROUND OF THE INVENTION

Fabricated farinaceous products prepared from starch-based flours arewell known in the art. Preparing such products from dehydratedingredients offers certain advantages such as homogeneity, uniformityand control of the end product. The food processor encounters severalproblems when formulating doughs used to prepare such products. Forexample, although a cohesive sheetable dough may be formed, the doughtypically falls apart or tears when sheeted at high speeds.Additionally, variability in the physical properties of the dehydratedingredients, in particular the flakes, often produces doughs that aresticky, tacky or gummy. This often leads to down time on processinglines and additional ingredient costs.

There are several problems associated with the physical properties ofconventional potato flakes and with the processes used to make suchflakes. One significant problem with conventional flakes is related tothe variability in the physical properties of the flakes produced frompotatoes. These variations are influenced by many factors such as typesof potatoes used to make the flakes, the season in which the potatoesare grown, when the potatoes are harvested, the area where the potatoesare grown, and the length of time the potatoes are stored. Thesevariations, up to now, have resulted in large variability between flakelots made from the potatoes.

The physical properties necessary in a flake used to formulate a doughfor making fabricated farinaceous products have gone unrecognized orunappreciated. While conventional processes try to minimize brokencells, it has been found that flakes comprising from about 40% to about60% broken cells are desirable from a sheeting standpoint. Further, ithas been found that controlling the difference between hot pasteviscosity and cold paste viscosity improves processability, even thoughconventional processes do not place any importance on this particularphysical property. It has also been found that a low water absorption isdesirable in a flake used for making a dough. While conventionalprocesses suggest a high water absorption index is desirable.

Conventional methods for processing potatoes into dehydrated productshave not allowed potato processors to produce suitable flakes frompotatoes of different variety, different compositions or from potatoby-products (e.g., potato pieces left over from French fry processes) orpotatoes from the beginning and end of season. Even when the samevariety of potatoes are used, there is an inability to consistentlycontrol the physical properties of the flakes by processing.

Several processes for making dehydrated potato flakes are disclosed inU.S. Pat. No. 2,787,533 issued to Cording et al., U.S. Pat. No.3,009,817 issued to Hendel, and U.S. Pat. No. 3,968,260 issued toShatilla et al. These patents disclose a process for preparing flakesfrom raw whole potatoes or conventional potato flakes but not fromslivers and nubbins. Further, these processes provide very few, if any,special measures that are designed to assure limited variability in thephysical properties of flakes. For example, prior to being cooked, thepotatoes are often pre-conditioned. The blanching toughens the potatocells, requires more energy to thoroughly cook the potatoes and makesuniform cooking of the potato pieces difficult. Additionally, thesequence of blanching, cooling, and cooking, as suggested by manyprocesses, increases retrogradation of starch and restricts the releaseof amylose and/or causes complexation of the free starch needed to forma cohesive machineable dough sheet. Moreover, cooking at hightemperatures and/or high steam pressures for short times or even at 212°F. (100° C.) for short times can result in potato flakes that areunder-cooked (e.g. raw or cooked on the outer surface) or over-cooked(e.g. having weak, swollen cells that will rupture during subsequentprocessing).

One process disclosed in U.S. Pat. No. 4,241,094 issued to O'Neal, makesdehydrated flakes by separating potatoes into two groups during theinitial processing. Later the two groups of flakes are blended to makedehydrated flakes, which have a texture and quality similar to freshlyprepared mashed potatoes when reconstituted. According to the O'Nealpatent, potato flakes made from mash having free starch throughout arepasty and undesirable. Further, retrogradation of starch is encouraged.Although the flakes may be suitable for the consumer to prepare mashedpotatoes, the potato flakes, due to their low level of free starch(amylose) and high water absorption index, are not desirable for theproduction of doughs from which fabricated farinaceous products aremade.

It can be seen that conventional processes are unsatisfactory for makingor providing dehydrated flakes having desirable properties.

A need exists for potato flakes made from various potatoes and potatoby-products. Another need exists for potato flakes having controlledphysical properties that are suitable for use in making farinaceousfabricated products. Further, a need exists for potato flakes and for amethod of producing potato flakes wherein the differences in performancefrom lot to lot is minimized.

Accordingly, it is an object of the present invention to provide aprocess for making dehydrated potato flakes.

It is another object of the present invention to provide potato flakesparticularly suitable for doughs used to make fabricated farinaceousproducts.

It is further an object of the present invention to provide potatoflakes having substantially improved processing qualities overconventionally-produced flakes.

These and other objects of the invention will become apparent from thefollowing disclosure and claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a graph showing the sheet strength test of a dough made fromthe potato flakes of the present invention;

FIG. 2 is a graph showing the sheet strength test of a dough made fromconventional the potato flakes;

FIG. 3 is a photomicrograph magnification 64× of potato cells in flakesmade according to the present invention.

FIG. 4 is a photomicrograph magnification 64× of potato cells in flakesmade according to conventional methods.

FIG. 5 is a graph showing the effects of various cooking conditionsincluding overcooking, undercooking and even cooking on the hot and coldpaste viscosities of potato flakes.

SUMMARY OF THE INVENTION

The present invention relates to dehydrated potato flakes that can beprepared from potato slices, slivers and/or nubbins. The presentinvention further relates to a process for producing potato flakeswherein the cooking cycle, during processing of the potato flakes, iscontrolled.

The process of the present invention is advantageous over processes inthat it allows the potato flake processor to produce flakes frompotatoes of different varieties and compositions and additionally toreduce the variability in the physical properties of the flakes producedfrom potatoes of different varieties and compositions. It further allowsthe flake producer to use slivers and nubbins, which were once thoughtto be unsuitable for use in the flaking process.

Use of the dehydrated flakes in the formulation of fabricatedfarinaceous products increases efficiency and allows the food processorto control the texture of the dough as well as the texture of theready-to-eat product.

In addition, the present invention relates to a dough containing thedehydrated potato flakes. The dough has increased sheet strength and canbe used to prepare farinaceous fabricated food products.

DETAILED DESCRIPTION

Definitions

As used herein, the term “slivers” refers to thin sliced potato piecesthat are separated from the products after the potato is cut into Frenchfry strips. These pieces are generally the by-products from the lengthportion of the French fry strip and are typically shorter than theFrench fry itself.

As used herein the term “nubbins” refers to short or broken potatopieces that are separated from the potato after it is cut into Frenchfry strips. These pieces are generally the by-products from the endportions of the French fry strip.

As used herein, “Brabender Units (BU)” is an arbitrary unit of viscositymeasurement roughly corresponding to centipoise.

As used herein, the term “fabricated farinaceous products” refers tofood products made from doughs that contain flour, meal or starchderived from tubers and/or grains.

As used herein “sheetable dough” is a dough capable of being placed on asmooth surface and rolled to the desired final thickness without tearingor forming holes.

As used herein “starch-based materials” refer to naturally occuring,high polymeric carbohydrates composed of glucopyranose units, in eithernatural, dehydrated (e.g., flakes, granules, meal) or flour form. Thestarch-based materials include, but are not limited to, potato flour,potato granules, corn flour, masa corn flour, corn grits, corn meal,rice flour, tapioca, buckwheat flour, rice flour, oat flour, bean flour,barley flour, tapioca, as well as modified starches, native starches,and dehydrated starches, starches derived from tubers, legumes andgrain, for example cornstarch, wheat starch, rice starch, waxy cornstarch, oat starch, cavassa starch, waxy barley, waxy rice starch,glutinous rice starch, sweet rice starch, amioca, potato starch, tapiocastarch, cornstarch, oat starch, cassaya starch, rice starch, wheatstarch, and mixtures thereof.

As used herein “Brabender Units (BU)” is an arbitrary unit of viscositymeasurement roughly corresponding to centipoise.

As used herein, “modified starch” refers to starch that has beenphysically or chemically altered to improve its functionalcharacteristics. Suitable modified starches include, but are not limitedto, pregelatinized starches, low viscosity starches (e.g., dextrins,acid-modified starches, oxidized starches, enzyme modified starches),stabilized starches (e.g., starch esters, starch ethers), cross-linkedstarches, starch sugars (e.g. glucose syrup, dextrose, isoglucose) andstarches that have received a combination of treatments (e.g.,cross-linking and gelatinization) and mixtures thereof.

As used herein, the term “added water” refers to water which has beenadded to the dry dough ingredients. Water which is inherently present inthe dry dough ingredients, such as in the case of the sources of flourand starches, is not included in the added water.

All percentages are by weight unless otherwise specified.

The present invention relates to a dehydrated potato flake havingcertain physical properties. Sheet strength, water absorption andstickiness of the dough can be controlled by the addition of thedehydrated flakes to the dough. Controlling the physical properties ofthe flakes allows one to also control the texture and fat content of theready-to-eat fabricated farinaceous product without adding additionalingredients (e.g., fibers, gums).

Any commercially-available potato used to prepare flakes can be used toprepare the dehydrated flakes of the present invention. Preferably, theflakes are prepared from potatoes such as, but not limited, to Kennebec,Russet Burbank, Id. Russet, Sebago, Bentgie, Aurora, Saturna, andMentor. Raw or pre-conditioned potato slices, nubbins and slivers ormixtures thereof can be used in the practice of the present invention.Typically, the nubbins and slivers will be pre-conditioned since theyare by-products of a standard French fry making process. The potatoflakes can be made using standard potato flake-making equipment, such asa twin or single screw cooker.

As used herein “potato pieces” refer to potato by-products, e.g.slivers, nubbins, or slabs. Potato pieces can be used in the practice ofthe present invention. In one preferred embodiment, raw potatoes arepeeled by steam and then inspected to remove defective potatoes. Thepeeling can be accomplished by lye, steam, or abrasion. The peeledpotatoes are sliced to a thickness of from about 0.25 to about 0.75inches, preferably from about 0.3 to about 0.7 inches and morepreferably from about 0.35 to about 0.65 inches (hereinafter referred toas “slabs”).

Next the raw potato pieces/slabs are cooked under atmospheric pressureusing steam typically having a pressure of from about 2 to about 50psig, preferably from about 2 to about 20 psig (pounds per square inchgauge), more preferably from about 5 to about 18 psig, and still morepreferably from about 10 to about 15 psig. The cooking process iscritical to obtaining the desired potato flake. The cooking process iscritical to obtaining the desired potato flake. The length of time toconduct the steaming and the cooking is, of course, dependent upon thevolume capacity of the vessel, the steam generator output, and theamount of potato pieces/slabs being cooked. Preferably the temperatureof the potato slab/pieces rises from about 65° F. (180° C.) to about212° F. (100° C.) during the first one-third of the cooking cycle, andthen maintained at a temperature of about 212° F. (100° C.) during theremainder of the cooking cycle. For example, if the total cooking timeis 30 minutes, it is important that the potato slabs/pieces receive aslow temperature rise in the first 10 minutes. It is also important thatthe potato slabs receive even cooking, and that the heating iscontinuous during at least the first one-third of the cooking cycle.Preferably, the heating is continuous throughout the cooking cycle andthe potatoes are not allowed to cool until cooking is complete. Thiswill allow the potato granules to sufficiently cook, swell, andgelatinize and will also allow some cells to shrink thereby increasingcell separation. Microscopic observations of potato cells frompieces/slabs that are prepared by heating the potato rapidly during thefirst one-third of the cooking cycle show that a case hardened surfaceforms on the outer portion of these potato cells and does not allow thepotato cells to swell properly. As temperature and pressure isincreased, the starch granules in the potato cells swell, gelatinize andburst [FIG. 4]. This results in flakes having a high water absorptionindex and low amylose content. If the potato pieces/slabs areundercooked, large amounts of raw starch can be seen in the microscopicobservation. Additionally, overcooked potato pieces/slabs show weakenedpotato cell walls which burst during subsequent processing. (Amylose istrapped within the gelatinized amylopectin structure.) This results inflakes having a measurable low level of soluble starch and high wateradsorption indexes. This is undesirable since high levels of gelatinized(amylopectin) starch will produce a sticky dough and since water will beremoved during subsequent cooking when the final farinaceous foodproduct is made. By contrast, microscopic evaluations of potatoespieces/slabs cooked by slowly raising the temperature during the firstone-third of the cooking cycle according to the present invention showswollen granules, cell separation and less than 60% broken cells [FIG.3].

The rate at which the potato pieces/slabs are heated during the firstone-third of the cooking cycle and the distribution of the steam isimportant as it affects the properties of the resulting dehydratedflakes. Preferably, the temperature rise from about 175° F. (79° C.) toabout 212° F. (100° C.) occurs over a time period more than about 10minutes, more preferably in more than about 15 minutes and even morepreferably in more than about 20 minutes. The total cooking time is atleast about 30 minutes, preferably from about 30 to about 65 minutes,and more preferably from about 50 to about 60 minutes.

The potato pieces/slabs can also be cooked using a pressurized vessel orSuperheated steam. The steam temperatures and pressures can varydepending on the equipment used. However, it is important that theresulting cooked potato pieces have swollen granules, cell separationand less than 60% broken cells.

After the steam cooking, the potato pieces/slabs are riced by forcingthe potato pieces through a slotted plate. Care must be taken not tobreak the cell structure. Generally, at least about 0.1% emulsifier isadded to the wet mash or cooked potatoes as a processing aid. Higherlevels of up to about 3% of an emulsifier can also be added, if needed,to complex the amylose if the resulting mash is too sticky (e.g., toomany broken cells due to overcooking). However, when the potatopieces/slabs are processed according to the present invention, highlevels of emulsifier (e.g. greater than 1%) should not be required.Preferably, the emulsifier is added to the mash upon exiting the ricerand prior to the flaking operation. The preferred emulsifier is adistilled monoglyceride and diglyceride of partially-hydrogenatedsoybean oil. Other emulsifiers suitable as processing aids in makingpotato flakes known in the art, e.g. lactylate esters, can also be used.

Additional ingredients can also be added to the wet mash to improve thestorage stability of the dehydrated potato flakes. Various stabilizersand preservatives are usually employed to improve the stability andtexture of the resulting flakes. For example, from about 150 to about200 parts per million (p.p.m.) of sulfite is provided in the dryproduct. This is added to the wet mash usually as dry sodium sulfite andsodium bisulfite and protects the flakes from darkening duringprocessing and subsequent storage. Antioxidants such as BHA (2 and3-tert-butyl-4-hydroxy-anisole) and BHT(3,5-di-tert-butyl-4-hydroxytoluene) are added in an amount up to atotal of about 10 p.p.m. to prevent oxidative deterioration. Citric acidis generally added in a quantity sufficient to give about 90 p.p.m. inthe dried product to prevent discoloration caused by the presence offerrous ions. Ascorbic acid can also be added to warrant the initiallevel of vitamins.

The potato mash is then subjected to a drying and flaking operation.Water may be added to the mash to increase heat transfer during drying.Suitable dryers can be selected from those well known drying devicessuch as fluidized bed dryers, scraped wall heat exchangers, drum dryers,and the like. A particularly preferred dryer is a drum dryer. The use ofdrum dryers is known in the potato industry.

When a drum dryer is used, the mash is fed to the top surface of thedrum by conveying means. Small diameter unheated rolls progressivelyapply fresh potato mash to portions already on the drum, thus buildingup a sheet. Peripheral speed of the small rolls is the same as that ofthe drum, and after traveling around the circumference of the drum adoctor knife removes the dried sheet by peeling the dried sheet awayfrom the drum. Typically, the drum dryer itself is heated totemperatures within the range of from about 300° F. to about 380,° F.preferably to a temperature of from about 330° F. to about 356° F. bypressurized steam contained within the drum at pressures of from about100 psig to about 132 psig. For optimum results the rotational speed ofthe dryer drum and the internal temperature thereof is suitablycontrolled so as to give a final product having a moisture content offrom about 5% to about 10%. Typically, a rotational speed of from about2 rpm to about 6 rpm, preferably about 2 rpm to about 4.5 rpm, issufficient.

The preferred process utilizes a twin double drum drier wherein the wetpotato mash is spread on the drum in a thin sheet having a thickness offrom 1 to about 5, preferably from about 4 to about 5, times thethickness of a single potato cell in an undried state, or about 0.007 toabout 0.010 inches.

Once the wet mash is sheeted and dried, the resulting dried sheet isthen comminuted with for example, an Urschel Comitrol, manufactured byUrschel Laboratories, Inc. of Valparaiso, Ind. Any method of comminutionthat minimizes the starch damage, such as grinding, cutting orpulverizing can be used.

The resulting dehydrated potato flakes comprise from about 19% to about27% amylose, from about 5% to about 10% moisture, at least about 0.1%emulsifier and a water absorption index of from about 7.7 to about 9.5.

In another embodiment, potato flakes are made from pre-conditionedpotato slabs, nubbins, and slivers or mixtures thereof. As used herein“pre-conditioned” refers to treatments such as blanching, watertransporting which causes the cells to toughen. The dehydrated potatoflakes can be made from slivers and nubbins (herein after refer to as“pieces”), as part or all of the potato ingredient, or the nubbins andslivers can be mixed together with potato slabs in the cooking process.Typically, the nubbins and slivers will be blanched since they are madein a standard French fry making process. The potato flakes can be madefrom about 5% to about 100% slivers, nubbins and mixtures thereof, andfrom about 0% to about 95% other potato pieces, typically slabs.Generally from about 5% to about 100% slivers, nubbins and mixturesthereof are used and from 0% to 95% potato slabs are used. Preferably,from about 20% to about 90% slivers, nubbins and mixtures thereof andfrom about 10% to about 80% potato slabs; more preferably from about 30%to about 80% slivers, nubbins and mixtures thereof and from about 20% toabout 70% potato slabs; even more preferably from about 40% to about 70%slivers, nubbins and mixtures thereof and from about 30% to about 60%potato slabs; and especially preferably from about 50% to about 60%slivers, nubbins and mixtures thereof and from about 40% to about 50%potato slabs are used.

It has been found that blanching or pre-conditioning potato pieces/slabscause the potato cells to toughen. As a result, when usingpre-conditioned potato pieces, additional energy is required to cook thepotato pieces properly (i.e., to obtain cooked potato pieces havingswollen granules, cell separation and less than 60% broken cells). Thepre-conditioning of the potato pieces/slabs causes the resulting potatoflakes to have a lower water absorption index (WAI), and a lowermeasurable amylose content than potato flakes produced from potatopieces/slabs that have not been pre-conditioned. However, the cookingprocess still requires controlling the rate at which the potato piecesare heated during the first one-third of the cooking cycle.

The increase in pressure and temperature needed to cook pre-conditionedpotato pieces causes the resulting flakes to have a lower waterabsorption index and a lower amylose content than potato flakes producedfrom potato pieces that are not pre-conditioned prior to the cooking.

The dehydrated potato flakes resulting from the process wherein thepotato pieces are pre-conditioned comprise from about 16% to about 20%amylose, from about 5% to about 10% moisture, at least about 0.1%emulsifier, and a water absorption index of from about 6.7 to about 8.3.

Therefore, within limits, the process of the present invention allowsone to produce end products having controlled and different physicalproperties which cannot be duplicated by potato flakes made by prior artprocess conditions.

Physical Properties of the Potato Flake

The potato flakes of the present invention have unique physicalproperties, in particular; (1) amylose content, (2) water absorptionindex, and (3) hot paste viscosity and cold paste viscosity. The methodsfor measuring the physical properties of the potato flakes are describedin the “Analytical Methods” disclosed below in the specification.

The potato flakes, when used in dough formulations, increase thecohesiveness, elasticity and sheeted strength of the dough.Additionally, use of the potato flakes of the present invention allowsthe food processor to control the amount of fat absorbed by the finishedproduct during cooking, if fried. This is surprising considering thefact that when conventional potato flakes are used in dough formulation,additional ingredients (e.g., binders, gums, and fibers) are required toachieve similar results. It is also surprising that the addition of thepotato flakes of the present invention to dough formulations improvesprocessability of the dough.

It has unexpectedly been found that improved processability of the doughis achieved partially by controlling the cold paste viscosity and hotpaste viscosity. This produces flakes that are stable (e.g., overvarious temperature ranges). In addition, it has also unexpectedly beenfound that the flakes of the present invention exhibit substantiallyimproved color stability and resist viscosity changes over time. Theseproperties have not been exhibited by potato flakes produced by knownprocesses.

The dehydrated potato flakes of the present invention comprise fromabout 40% to about 60% broken cells, from about 16% to about 27%amylose, from about 5% to about 10% moisture, and at least about 0.1%emulsifier. Additionally, the dehydrated flakes of the present inventionhave a water absorption index of from about 6.7 to about 9.5 grams ofwater per gram of flakes, a hot paste viscosity of from about 100 BU toabout 320 BU and a cold paste viscosity of from about 100 BU to about230 BU. From about 20% to about 40% of the dehydrated potato flakesremain on a #40 U.S. screen.

Broken Cells

The dehydrated potato flakes of the present invention comprise fromabout 40% to about 60% broken cells, preferably from about 45% to about55% and more preferably about 50% broken cells. The percentage of brokencells is determined by light microscope and is an indication of thedegree of cook and starch damage that has occurred during ricing andgrinding. A large number of broken cells indicate improper processingconditions, such as, overcooking, use of too much shear and/or reducingthe particle size of the potatoes by using an apparatus that applies toomuch shear,(e.g. a hammer mill) among other things.

Amylose—A (%)

The dehydrated potato flakes also comprise from about 16% to about 27%amylose (A %). The amylose is a measurement of the free starch in thepotato flake composition. The level of amylose is controlled bymaintaining a slow but constant temperature rise during the first ⅓ ofthe cooking cycle and by controlling the grinding step of the potatoflaking process.

Dehydrated potato flakes made from pre-conditioned potato piecescomprise from about 16% to about 20% amylose, preferably about fromabout 17% to about 19% amylose, and more preferably about 18% amylose.

Dehydrated potato flakes made from pre-conditioned, or unpre-conditionedbut pre-conditioned flakes by transporting them in cold water, potatopieces comprise from about 16% to about 20% amylose, preferably aboutfrom about 17% to about 19% amylose, and more preferably about 18%amylose.

Moisture

The dehydrated potato flakes of the present invention comprise fromabout 5% to about 10%, preferably about 6% to about 9%, and morepreferably from about 7% to about 8% moisture.

Emulsifier

Typically an emulsifier is present in the flake because of its use as aprocessing aid to prevent the potato mash from sticking to the rollerduring drying and flaking. Therefore, low levels of emulsifiers arepresent in the flake.

Typically the emulsifier is present in the flake at a level of fromabout 0.1% to about 1%. Preferably, the emulsifier is present in theflake at a level of from about 0.1% to about 0.5%, more preferably atabout 0.2% to about 0.4%. Higher levels of emulsifiers can be present,for example, if the potatoes are overcooked and high levels of amyloseare present in the potato mash. In these instances, the emulsifier maybe present in a level as high as 3%. If the potato has been undercooked,the addition of emulsifiers will not correct the texture of theundercooked mash because of the large amount of raw starch.

Water Absorption Index (WAI)

Water absorption index is a physical parameter that indicates thecapacity of a material such as potato flakes to hold water. It isdirectly proportioned to the degree of cooking. It theoreticallycorrelates to the physical damage of the potato cells in the potatoflakes. WAI also correlates in a small degree to surface area exposed asa result of grinding. In the process of making fabricated chips, the WAIis believed to correlate to the level of fat that will be absorbed inthe final product during the frying process.

Dehydrated potato flakes made from raw potato pieces have a WAI of fromabout 7.7 to about 9.5 grams of water per gram of flakes, preferablyfrom about 8 to about 9 grams of water per gram of flakes.

Dehydrated potato flakes that are made from pre-conditioned potatopieces have a WAI of from about 6.7 to about 8.3, preferably about 7 toabout 8, grams of water per gram of flakes.

Hot Paste Viscosity (HPV) and Cold Paste Viscosity (CPV)

The hot paste viscosity (HPV) is a measurement of the highest viscositypeak of a starch material after applying high temperatures underconstant shear rate. The initial part of the viscosity profile curvestrongly correlates to WAI. For native starches, the hot paste viscosityprofile will show a maximum peak viscosity in the range of thegelatinization temperature. In the case of potato flakes, as well asother partially gelatinized starches, the HPV is used as an indicationof the degree of cooking and cell damage. The higher HPV profilesindicate more cell damage due to overcooking in the flaking process[FIG. 5]. Large differences between HPV arid cold paste viscosityindicate uneven cooking [FIG. 5] in the flakes of the present inventionThe difference between the HPV and CPV is preferably less than about 150BU, more preferably less than about 120 Brabender Units (BU), and evenmore preferably less than about 100 BU. These differences indicate evencooking [FIG. 5 “control”].

Cold paste viscosity (CPV) is a measurement of the highest peakviscosity of a starch material at low temperatures under a constantshear rate. The cooling part of the viscosity profile curve stronglycorrelates to the free amylose level in the sample. For overcookedstarches, the CPV increases [FIG. 5]. The cooling curve is an indicationof the starch retrogradation happening during the process. The HPV andCPV are measured in Brabender Units (BU) which is an arbitrary unit ofviscosity measurement, roughly correlating to centipoise.

Dehydrated potato flakes made from raw potato pieces have a HPV of fromabout 240 BU to about 320 BU, preferably from about 260 BU to about 300BU, and more preferably from about 275 BU to about 290 BU; and a CPV offrom about 120 BU to about 230 BU, preferably from about 150 BU to about220 BU and more preferably from about 170 BU to about 210 BU.

Dehydrated potato flakes made from pre-conditioned potato pieces have aHPV of from about 100 to about 280 BU, preferably 150 by to about 250 BUand more preferably from 190 by to about 230 BU; and a CPV of from about100 by to about 200, preferably from about 120 by to about 210 by andmore preferably 140 by to about 160. Analysis of the HPV and CPVprepared by prior art processes dehydrated potato flakes have a HPV andCPV that increase over time. In contrast to flakes of the presentinvention, flakes prepared by prior art processes have HPV and CPVdifferences of greater than 120 BU's as compared to flakes of thepresent invention.

Particle Size Distribution

The particle size of the dehydrated potato flakes of the presentinvention is reduced such that from 60% to about 70% remain as a #100U.S. screen, from a 20% to about 40% remain on a #40 U.S. screen, fromabout 1 to about 3% remain on a #20 U.S. screen and from 1% to about 3%remain on a #16 U.S. screen. Particle size distribution is a measure ofthe granularity of the flakes. It is generally a weight-baseddistribution of flakes based on the size of particles. Normally, it isdescribed by a set of U.S. standard measure sizes. Reducing the size ofthe dehydrated flakes such that there are more fines can change thephysical properties of the flake. For example, reducing the particlesize results in an increased amylose content and an increase in thenumber of broken cells, as well as a change in WAI.

Dough

Another embodiment of the present invention includes using thedehydrated flake in a composition for dough. The dough can be used tomake fabricated farinaceous food products. The addition of thedehydrated flakes to the dough increases the sheet strength of the doughand gives food processors flexibility to control the properties of thedough and final products made from the dough.

Typically, the dough is used to make fabricated potato chips. However,the dough can also be used to make other farinaceous products which aresheeted or extruded (e.g., chips, tortilla chips, pretzels, crackers andthe like, hereinafter referred to as “snacks”). The dough composition ofthe present invention comprise:

-   -   (a) from about 50% to about 70% of a starch-based material        wherein said starch-based material comprises up to 100% potato        flakes of this invention;    -   (b) at least about 3% hydrolyzed starches having a D.E. of from        about 5 to about 30; and    -   (c) from about 20% to about 46.5% added water.

Optionally, from about 0.5% to about 6% of emulsifier may be added tothe dough compositions as a processing aid.

The doughs of the present invention additionally have a sheet strengthbetween about 140 and 625 grams force (gf).

The doughs of the present invention can comprise from about 50% to about70%, preferably from about 55% to about 65%, and more preferably about60% of a starch-based material. The starch-based material can comprisefrom about 25 to 100% potato flakes of the present invention, with thebalance (i.e., from 0% to about 75%) being other starch-containingingredients such as potato flour, potato granules, corn flour, masa cornflour, corn grits, corn meal, rice flour, tapioca, buckwheat flour, riceflour, oat flour, bean flour, barley flour, tapioca, as well as modifiedstarches, native starches, and dehydrated starches, starches derivedfrom tubers, legumes and grain, for example cornstarch, wheat starch,rice starch, waxy corn starch, oat starch, cavassa starch, waxy barley,waxy rice starch, glutinous rice starch, sweet rice starch, amioca,potato starch, tapioca starch, cornstarch, oat starch, cassaya starch,rice starch, wheat starch, and mixtures thereof. The starch-basedmaterial preferably comprises from about 40% to about 90%, morepreferably from about 50% to about 80%, and even more preferably about60% to about 70%, potato flakes of the present invention, and from about10% to about 60%, preferably from about 20% to about 50%, and morepreferably from about 30% to about 40%, of these other starch-containingingredients.

Particularly preferred starch-based materials of the present inventionare made from dehydrated potato flakes of the present invention andpotato granules wherein the potato flakes comprise from about 25% toabout 95%, preferably from about 35% to about 90%, and more preferablyfrom about 45% to about 80% of the starch-based material, and the potatogranules comprise from about 5% to about 75%, preferably from about 10%to about 65%, and more preferably from about 20% to about 55%, of thestarch-based material.

Another preferred embodiment can be made using a mixture of the potatoflakes of the present invention and potato granules, combined with otherstarch-containing ingredients that are not potato flakes or granules.Typically, the combined flakes and granules comprise from about 40% toabout 90%, preferably from about 50% to about 80%, and more preferablyfrom about 60% to about 70% of the starch-based material, while theother non potato flake/granule starch-containing ingredients comprisefrom about 10% to about 70%, preferably from about 20% to about 50%, andmore preferably from about 30% to about 40%, of the starch-basedmaterials.

The dough compositions of the present invention comprise from about 20%to about 46.5% added water, preferably from about 22% to about 40%, andmore preferably from about 24% to about 35%, added water. As usedherein, the term “added water” refers to water which has been added tothe dry dough ingredients. Water which is inherently present in the drydough ingredients, such as in the case of the sources of flour andstarches, is not included in the added water. The level of water inflours and starches is usually from about 3% to about 8%. However, ifthe maltodextrin or corn syrup solids are added as a solution or syrup,the water in this syrup or solution must be accounted for as “addedwater”. The amount of added water includes any water used to dissolve ordisperse ingredients, as well as water present in corn syrups, etc.

In addition to the starch-based material and water, the doughcompositions comprise other ingredients that aid in processability.These ingredients are particularly important when processing a doughthat is to be sheeted on a continuous basis. The additional ingredientsinclude, but are not limited to, hydrolyzed starches and emulsifiers.

Hydrolyzed starches are important to the processability of the doughs ofthe present invention which have relatively low water levels. In theabsence of hydrolyzed starches, low moisture levels in the dough; canprevent formation of a continuous, smooth extensible dough sheet; canhinder subsequent expansion of the dough pieces during frying; andaffects the elasticity of the dough. Although the dough compositions canbe sheeted without the inclusion of hydrolyzed starches, the resultingsnack has a foamy texture and high fat. Hydrolyzed starches reduce thework input to the dough, reducing the amount of water needed to sheetthe dough. This in turn reduces fat.

Hydrolyzed starches can be included in the dough compositions in anamount of at least about 3%, with a usual range of from about 3% toabout 15%. Preferably, hydrolyzed starches are included in an amount offrom about 5% to about 12%. Suitable hydrolyzed starches for inclusionin the dough include maltodextrins and corn syrup solids. The hydrolyzedstarches for inclusion in the dough have Dextrose Equivalent (D.E.)values of from about 5 to about 30, preferably from about 10 to about20. Maltrin™ M050, M100, M150, M180, M200, and M250 (available fromGrain Processing Corporation, Iowa) are preferred maltodextrins. TheD.E. value is a measure of the reducing equivalence of the hydrolyzedstarch referenced to dextrose and is expressed as a percentage (on a drybasis). The higher the D.E. value, the more reducing sugars are present.

Emulsifiers

Another ingredient that can be added optionally to the doughcompositions to aid in the processability of the dough is an emulsifier.The emulsifier works via several mechanisms. The first is as a coatingof the flour in the mixer just prior to the addition of the water. Thislimits the moisture absorption of the flour producing a “short” dough.The second function of the emulsifier is to create a dispersion of fatand moisture droplets throughout the dough. Both of these mechanism tendto limit the adhesiveness of the starch contained in the flour,preventing permanent adhesion to the sheeting rolls.

An emulsifier is preferably added to the dough composition prior tosheeting the dough. The emulsifier can be dissolved in a fat or in apolyol fatty acid polyester, preferably a sucrose fatty acid polyestersuch as Olean™, available from The Procter and Gamble Company. Suitableemulsifiers include mono- and diglycerides, diacetyl tartaric acidesters and propylene glycol mono- and diesters and polyglycerol.Polyglycerol emulsifiers such as monoesters of polyglycerols, preferablyhexapolyglycerols can be used.

Particularly preferred emulsifiers comprise a blend of from about 42.5%to about 90%, preferably from about 50% to about 85%, more preferablyfrom about 60% to about 80%, non-digestible fat with the balance being amixture of di-glyceride, triglyceride, and preferably a monoglyceridewherein the level of monoglyceride is at least about 30%, and istypically from about 30% to about 95%, preferably from about 50% toabout 90% wherein the monglyceride has an IV of greater than about 60,preferably an IV between about 70 to about 120, more preferably an IV offrom about 80 to about 110, even more preferably an IV of from about 90to about 100.

Preferably, the mono-glyceride is a distilled monoglyceride having an IVof about 60, derived from, for example, soybean oil, rapeseed oil,cottonseed oil, sunflower seed oil, palm oil, palm olein, safflower oil,corn oil, peanut oil and mixtures thereof. The preferred distilledmonoglycerides include but are not limited to monoglycerides derivedfrom, soybean oil, rapeseed and palm oil and mixtures thereof.

Typically commercially available mono-glycerides contain varying amountsof di- and tri-glycerides. For example, distilled monodiglyceridecomprise about 90% monoglyceride while monodiglycerides comprise about30% mono-glycerides. Either can be used in the dough formulations of thepresent invention.

A particularly preferred monoglyceride is sold under the trade names ofDimodan® available from Danisco, New Century, Kans. and DMG 70,available from Archer Daniels Midland Company, Decatur, Ill.

The level of added emulsifier depends on the amount of work input thatthe dough will receive in subsequent processing (e.g., extrusion,sheeting) steps. As used herein, the term “added emulsifier” refers toan emulsifier which has been added to the dry dough ingredients.Emulsifiers which are inherently present in the dry dough ingredients,such as in the case of the potato flakes, are not included in the term“added emulsifier.”

The need for higher levels of emulsifier increases as work inputincreases. Typically, if the doughs are to be sheeted, emulsifiers areadded to the dough in an amount of from about 0.5% to about 6.0% byweight, preferably from about 1.0% to about 5.0%, more preferably fromabout 2 to about 4% and most preferably about 3%. Emulsifiers levelshigher than this result in sheet tears and pinholes.

Additional Ingredients

Additional ingredients can also be added to the dough compositions.These ingredients include vitamins, salt, flavorings, flavorpotentiators, and/or seasonings. Particularly preferred is the use ofVitamin C. Vitamin C can be present in the dough compositions at a levelof from about 0.01% to about 0.10%, preferably at a level of from about0.02% to about 0.08%, more preferably at a level of from about 0.03% toabout 0.07%, and even more preferably at a level of from about 0.04% toabout 0.06%. Preferably the dough is fortified such that the final snackcomprise from about 2 mg. to about 8 mg., preferably from about 4 mg. toabout 6 mg. of Vitamin C per one ounce serving of snack. The additionalingredients can be included in the dough or sprinkled or sprayed on thesurface of the snack after frying.

Sheet Strength

The dough compositions containing the potato flakes of the presentinvention exhibit substantially improved sheet strength as compared todoughs of the same composition made with prior conventional potatoflakes. The sheet strength is a measurement of the force needed to breaka piece of dough. The sheet strength correlates with cohesiveness of thedough and the ability of the dough to resist developing holes and/ortearing during subsequent processing steps.

The sheet strength of the doughs of the present invention increases asthe amount of energy input during the dough making step increases.Factors which can affect energy input include, but are not limited to,mixing conditions, dough sheet formation, and the amount of measurableamylose. For example, doughs mixed in a conventional low work inputmixer, for example a Hobart® or Cuisinart ® will typically have a sheetstrength more preferably less than about 100 BU. These differencesindicate even cooking [FIG. 5 “control”].

Dough compositions receiving relatively low work input comprising potatoflakes made from raw potato pieces typically have a sheet strengthmeasurement of from about 170 gf to about 250 gf, preferably from about180 gf to about 240 gf, and more preferably from about 190 gf to about220 gf.

Dough compositions receiving relatively low work input comprising potatoflakes made from pre-conditioned potato pieces typically have a sheetstrength measurement of from about 140 gf to about 200 gf, preferablyfrom about 155 gf to about 190 gf, and more preferably from about 165 gfto about 185 gf.

Doughs produced on a commercial scale where higher work input mixers,for example a Turboilizer® or extruder are used, the sheet strength isgenerally about 1.5 times to about 2.5 times the sheet strength of thedoughs produced from the low work input mixer.

As shown in FIG. 2, doughs made under same work input usingconventionally made flakes have a sheet strength lower than the doughsof the present invention.

Preferably, doughs produced from a high work input mixer have a sheetstrength between about 210 and about 625 gf, preferably from about 225gf and about 560 gf, more preferably from about 245 gf and about 500 gf,even more preferably from about 265 gf to about 480 gf, and especiallypreferably from about 200 gf to about 400 gf.

A. Dough Preparation

The dough compositions of the present invention can be prepared by anysuitable method for forming sheetable doughs. Typically, a loose, drydough is prepared by thoroughly mixing together the flakes, granules andother starch-based materials and optionally an emulsifier and sucrosefatty acid polyester combination. A water pre-blend of flavoring(optional), hydrolyzed starches, sucrose and/or salt are separatelymixed to obtain the previously defined hydrolyzed starch and waterlevels. The water pre-blend is then added to the starch-based materialmixture and emulsifier blend. Preferred devices for mixing together thedough ingredients are conventional mixers. Hobart® mixers are used forbatch operations and Turbolizer® mixers can be used for continuousmixing operations. However, extruders can also be used to mix the doughand to form the sheets or shaped pieces.

B. Sheeting, Snack Piece Formation and Frying

Once prepared, the dough is then formed into a relatively flat, thinsheet. Any method suitable for forming such sheets from starch-baseddoughs can be used. For example, the sheet can be rolled out between twocounter rotating cylindrical rollers to obtain a uniform, relativelythin sheet of dough material. Any conventional sheeting, milling andgauging equipment can be used. The mill rolls should be heated to about90° F. (32° C.) to about 135° F. (57° C.). In a preferred embodiment,the mill rolls are kept at two different temperatures, with the frontroller being cooler than the back roller.

Dough compositions of the present invention are usually formed into asheet having a thickness of from about 0.015 to about 0.10 inches (fromabout 0.038 to about 0.25 cm), and preferably to a thickness of fromabout 0.05 to about 0.10 inches (from about 0.013 to about 0.025 cm),and most preferably from about 0.065 inches to about 0.080 inches (1.65to 2.03 mm). For rippled (wavy shaped) chips, the preferred thickness isabout 0.75 inches (1.9 mm). The dough sheet is then formed into snackpieces of a predetermined size and shape. The snack pieces can be formedusing any suitable stamping or cutting equipment. The snack pieces canbe formed into a variety of shapes. For example, the snack pieces can bein the shape of ovals, squares, circles, a bowtie, a star wheel, or apin wheel. The pieces can be scored to make rippled chips as describedin published PCT application WO 95/07610, Dawes et al., Jan. 25, 1996,which is incorporated by reference.

After the snack pieces are formed, they are cooked until crisp. Thesnack pieces may be cooked by baking, frying, and combinations thereof.For example the chips can be fried only, baked only, partially friedthen baked or partially baked then fried.

The snack pieces may be baked at a temperature between about 300° F.(149° C.) to about 450° F. (232° C.) for a time sufficient to form askin the surface of the chips, and then fried to doneness. If desired,the snack pieces can also be fried to moisture content of 10% or lessand then heated with hot air, superheated steam or inert gas to lowerthe moisture level to 4% or less. This is a combined frying/baking step.

It is preferred to fry the snack pieces in oil at temperatures fromabout 275° F. (135° C.) and about 400° F. (204° C.), preferably fromabout 300° F. (149° C.) to about 375° F. (191° C.), and more preferablyfrom about 315° F. (157C) to about 350° F. (177C) for a time sufficientto form a product having from about 0.5% to about 6%, preferably fromabout 1% to about 5%, and more preferably from about 2% to about 4%moisture. The exact fry time is controlled by the temperature of thefrying fat and the starting water content. The fry time and temperaturecan be easily determined by one skilled in the art.

Preferably the snack pieces are fried in frying fat using a continuousfrying method and are constrained during frying. This constrained fryingmethod and apparatus is described in U.S. Pat. No. 3,626,466 (Liepa,1971). The shaped, constrained pieces are passed through the fryingmedium until they are fried to a crisp state with a final moisturecontent of about 0.5% to about 4% water, preferably 1% to 2%.

Continuous frying or batch frying of the snack pieces in anon-constrained mode is also acceptable. In this method, the pieces areimmersed in the frying fat on a moving belt or basket.

The frying can be done in convention triglyceride oils, or, if desired,the frying can be done in low calorie fat-like materials such as thosedescribed in U.S. Pat. No. 3,600,186 to Mattson et al. (assigned to TheProcter & Gamble Co), issued May 12, 1970; U.S. Pat. No. 4,005,195 toJandacek (assigned to The Procter & Gamble Co.), issued Jan. 25, 1977;U.S. Pat. No. 4,005,196 to Jandacek et al. (assigned to The Procter &Gamble Co.), issued Jan. 25, 1977; U.S. Pat. No. 4,034,083 to Mattson(assigned to The Procter & Gamble Co.), issued Jul. 5, 1977; and U.S.Pat. No. 4,241,054 to Volpenhein et al. (assigned to The Procter &Gamble Co.), issued Dec. 23, 1980, all of which are incorporated byreference herein. Frying can also be done in mixtures of conventionaltriglyceride oils and non-digestible oils.

The terms “fat” and “oil” are used interchangeably herein unlessotherwise specified. The terms “fat” or “oil” refer to edible fattysubstances in a general sense, including natural or synthetic fats andoils consisting essentially of triglycerides, such as, for examplesoybean oil, corn oil, cottonseed oil, sunflower oil, palm oil, coconutoil, canola oil, fish oil, lard and tallow, which may have beenpartially or completely hydrogenated or modified otherwise, as well asnon-toxic fatty materials having properties similar to triglycerides,herein referred to as non-digestible fat, which materials may bepartially or fully indigestible. Reduced calorie fats and ediblenon-digestible fats, oils or fat substitutes are also included in theterm.

The term “non-digestible fat” refers to those edible fatty materialsthat are partially or totally indigestible, e.g., polyol fatty acidpolyesters, such as OLEAN™.

The terms “fat” or “oil” also refer 100% non-toxic fatty materialshaving properties similar to triglycerides. The terms “fat” or “oil” ingeneral include fat-substitutes, which materials may be partially orfully non-digestible.

By “polyol” is meant a polyhydric alcohol containing at least 4,preferably from 4 to 11 hydroxyl groups. Polyols include sugars (i.e.,monosaccharides, disaccharides, and trisaccharides), sugar alcohols,other sugar derivatives (i.e., alkyl glucosides), polyglycerols such asdiglycerol and triglycerol, pentearythritol, sugar ethers such assorbitan and polyvinyl alcohols. Specific examples of suitable sugars,sugar alcohols and sugar derivatives include xylose, arabinose, ribose,xylitol, erythritol, glucose, methyl glucoside, mannose, galactose,fructose, sorbitol, maltose, lactose, sucrose, raffinose, andmaltotriose.

By “polyol fatty acid polyester” is meant a polyol having at least 4fatty acid ester groups. Polyol fatty acid esters that contain 3 or lessfatty acid ester groups are generally digested in, and the products ofdigestion are absorbed from, the intestinal tract much in the manner ofordinary triglyceride fats or oils, whereas those polyol fatty acidesters containing 4 or more fatty acid ester groups are substantiallynon-digestible and consequently non-absorbable by the human body. It isnot necessary that all of the hydroxyl groups of the polyol beesterified, but it is preferable that disaccharide molecules contain nomore than 3 unesterified hydroxyl groups for the purpose of beingnon-digestible. Typically, substantially all, e.g., at least about 85%,of the hydroxyl groups of the polyol are esterified. In the case ofsucrose polyesters, typically from about 7 to 8 of the hydroxyl groupsof the polyol are esterified.

The polyol fatty acid esters typically contain fatty acid radicalstypically having at least 4 carbon atoms and up to 26 carbon atoms.These fatty acid radicals can be derived from naturally occurring orsynthetic fatty acids. The fatty acid radicals can be saturated orunsaturated, including positional or geometric isomers, e.g., cis- ortrans-isomers, and can be the same for all ester groups, or can bemixtures of different fatty acids.

Liquid non-digestible oils can also be used in the practice of thepresent invention. Liquid non-digestible oils have a complete meltingpoint below about 37° C. include liquid polyol fatty acid polyesters(see Jandacek; U.S. Pat. No. 4,005,195; issued Jan. 25, 1977); liquidesters of tricarballylic acids (see Hamm; U.S. Pat. No. 4,508,746;issued Apr. 2, 1985); liquid diesters of dicarboxylic acids such asderivatives of malonic and succinic acid (see Fulcher; U.S. Pat. No.4,582,927; issued Apr. 15, 1986); liquid triglycerides of alpha-branchedchain carboxylic acids (see Whyte; U.S. Pat. No. 3,579,548; issued May18, 1971); liquid ethers and ether esters containing the neopentylmoiety (see Minich; U.S. Pat. No. 2,962,419; issued Nov. 29, 1960);liquid fatty polyethers of polyglycerol (See Hunter et al; U.S. Pat. No.3,932,532; issued Jan. 13, 1976); liquid alkyl glycoside fatty acidpolyesters (see Meyer et al; U.S. Pat. No. 4,840,815; issued Jun. 20,1989); liquid polyesters of two ether linked hydroxypolycarboxylic acids(e.g., citric or isocitric acid) (see Huhn et al; U.S. Pat. No.4,888,195; issued Dec. 19, 1988); various liquid esterfied alkoxylatedpolyols including liquid esters of epoxide-extended polyols such asliquid esterified propoxylated glycerins (see White et al; U.S. Pat. No.4,861,613; issued Aug. 29, 1989; Cooper et al; U.S. Pat. No. 5,399,729;issued Mar. 21, 1995; Mazurek; U.S. Pat. No. 5,589,217; issued Dec. 31,1996; and Mazurek; U.S. Pat. No. 5,597,605; issued Jan. 28, 1997);liquid esterified ethoxylated sugar and sugar alcohol esters (see Enniset al; U.S. Pat. No. 5,077,073); liquid esterified ethoxylated alkylglycosides (see Ennis et al; U.S. Pat. No. 5,059,443, issued Oct. 22,1991); liquid esterified alkoxylated polysaccharides (see Cooper; U.S.Pat. No. 5,273,772; issued Dec. 28, 1993); liquid linked esterifiedalkoxylated polyols (see Ferenz; U.S. Pat. No. 5,427,815; issued Jun.27, 1995 and Ferenz et al; U.S. Pat. No. 5,374,446; issued Dec. 20,1994); liquid esterfied polyoxyalkylene block copolymers (see Cooper;U.S. Pat. No. 5,308,634; issued May 3, 1994); liquid esterifiedpolyethers containing ring-opened oxolane units (see Cooper; U.S. Pat.No. 5,389,392; issued Feb. 14, 1995); liquid alkoxylated polyglycerolpolyesters (see Harris; U.S. Pat. No. 5,399,371; issued Mar. 21, 1995);liquid partially esterified polysaccharides (see White; U.S. Pat. No.4,959,466; issued Sep. 25, 1990); as well as liquid polydimethylsiloxanes (e.g., Fluid Silicones available from Dow Corning). All of theforegoing patents relating to the liquid nondigestible oil component areincorporated herein by reference. Solid non-digestible fats or othersolid materials can be added to the liquid non-digestible oils toprevent passive oil loss. Particularly preferred non-digestible fatcompositions include those described in U.S. Pat. No. 5,490,995 issuedto Corrigan, 1996, U.S. Pat. No. 5,480,667 issued to Corrigan et al,1996, U.S. Pat. No. 5,451,416 issued to Johnston et al, 1995 and U.S.Pat. No. 5,422,131 issued to Elsen et al, 1995. U.S. Pat. No. 5,419,925issued to Seiden et al, 1995 describes mixtures of reduced calorietriglycerides and polyol polyesters that can be used herein. However thelatter composition may provide more digestible fat.

The preferred non-digestible fats are fatty materials having propertiessimilar to triglycerides such as sucrose polyesters. OLEAN,™ a preferrednon-digestible fat, is made by The Procter and Gamble Company. Thesepreferred non-digestible fats or oil substitute compositions aredescribed in Young; et al., U.S. Pat. No. 5,085,884, issued Feb. 4,1992, and U.S. Pat. No. 5,422,131, issued Jun. 6, 1995 to Elsen et al.

Other ingredients known in the art may also be added to the edible fatsand oils, including antioxidants such as TBHQ ascorbic acid, chelatingagents such as citric acid, and anti-foaming agents such asdimethylpolysiloxane.

The snack products made from this process typically have from about 19%to about 38%, preferably from about 20% to about 35%, and morepreferably from about 23% to about 32% fat. If a higher fat level isdesired in the snack product to further improve the lubricity of thesnack, oil can be sprayed onto the snack product when it emerges fromthe fryer, or when it is removed from the mold used in constrainedfrying. Preferably the oils for spraying will have an iodine valuegreater than 75, and most preferably above 90. Oils with characteristicflavors or highly unsaturated oils can be sprayed onto the snackproduct. Oils with added flavors can also be used. These include butterflavored oils, natural or artificial flavored oils, herb oils and oilswith garlic or onion flavors added. This is a way to introduce a varietyof flavors without having the flavor undergo browning reactions duringthe frying. It also avoids adding the flavor to the dough and having theflavor react with or leach into the oil during the frying process. Thismethod can be used to introduce healthier oils which would ordinarilyundergo polymerization or oxidation during the heating necessary to frythe snacks.

Oil spray can be applied to the snack product after baking or frying.The oil may be used to increase the fat content of the snack to a fatcontent as high as 44% oil. Thus a snack product having various fatcontents can be made using this additional step.

Analytical Methods

Water Absorption Index (WAI)

In general, the terms “Water Absorption Index” and “WAI” refer to themeasurement of the water-holding capacity of any carbohydrate basedmaterial as a result of a cooking process. (See for example Anderson, R.A., Conway, H. F., Pfeifer, V. F. and Griffin, Jr., E. L., 1969,Gelatinization of Corn Grits By Roll- and Extrusion-Cooking. CEREALSCIENCE TODAY; 14(1):4). The cooking and dehydration of potato flakesintroduces changes in the potato cell physiology which affects itsrehydration properties, specifically its water-holding capacity. Thismeasurement is typically expressed as the ratio of mass of water heldper unit mass of material.

The WAI for a sample is determined by the following procedure: Theweight to two decimal places of an empty centrifuge tube is determined.Two grams of dry sample (e.g., potato flakes) are placed into the tube.Thirty milliliters of water is added to the tube. The water and sampleare stirred vigorously to insure no dry lumps remain. The tube is placedin a 30° C. (85° F.) water bath for 30 minutes, repeating the stirringprocedure at 10 and 20 minutes. The tube is then centrifuged for 15minutes at 3,000 RPM. The water is then decanted from the tube, leavinga gel behind. The tube and contents are weighed. The WAI is calculatedby dividing the weight of the resulting gel by the weight of the drysample (i.e., [weight of tube and gel]−[weight of tube]÷[weight of dryflakes]).

Percent Amylose (A %) test

This method is designed to measure the percentage (relative quantity) ofamylose in potato flakes which is soluble in 0.1N NaOH solution underspecific test conditions. Flakes are stirred in a base solution at 60°C. for 30 minutes, centrifuged, and the clear supernatant is thenreacted with iodine and analyzed spectrophotometrically. The amylose ismeasured as the iodine complexes at 700 nm, rather than 610 nm, to avoidthe interference from the “amylopectin-I₂ complex”.

Apparatus

Volumetric flakes, volumetric pipettes, balance, spectrophotometer(Beckman Model 24 or equivalent), cells (1 cm disposable, MarksmanScience #1-P-10, or 1 cam sipper type Markson MB-178 or Beckman Part#579215), constant temperature bath, blender and blender jars.

Reagents

Sodium Hydroxide Solution 0.1N, Hydrochloric Acid, Iodine, PotassiumIodide, Calibration Standard (Amylose—Sigma Type III potato cat. #A-0512).

Preparation of Solutions

A. Stock Iodine Solution

Weigh 2 g of Iodine and 20 g of Potassium Iodide into a red 250 mlvolumetric flask, and dissolve with distilled water.

B. Reagent Iodine Solution

Pipet 10 ml of the stock Iodine solution and 2 ml of concentratedhydrochloric acid into a red 1000 ml volumetric flask. Dilute to volumewith distilled water.

Standard Curve Preparation Using Standard Amylose

-   1. Dissolve 1 g of amylose (Sigma, from potato) with 100 0.1N NaOH.    Transfer entire solution into a centrifuge bottle, without rinsing.    Centrifuge at 1600 rpm for 15 min.-   2. Prepare three dilutions: a) 10 ml of supernatant into 100 ml of    0.1N NaOH, b) 5 ml of supernatant of first dilution into 100 ml of    0.1N NaOH, and c) 50 ml of the second dilution into 100 ml of 0.1N    NaOH.    Sample Preparation-   1. Obtain percent moisture in each sample. (Vacuum oven 16 hours 70°    C., or 3 hr @ 130° C. in an air oven).-   2. Weigh 0.2 g of potato flakes and dissolve with 100 ml of 0.1 N    NaOH solution. Turn the stirrer on high to obtain a good vortex in    the liquid.-   3. Place samples in the 60° C. water bath. Stir for 30 minutes.    Remove from bath.-   4. Pour the entire solution into a centrifuge bottle; do not rinse.    Centrifuge at 1600 rpm for 15 minutes.-   5. Pipet 1 ml of the supernatant into a 25 ml volumetric flask.    Dilute all the volume with iodine reagent. Prepare the blank    solution, using 1 ml of the 0.1N NaOH solution in a 25 ml flask.    Shake well. The calorimetric determination must be made 10–30    minutes after mixing.    Colorimetric Determination

Set the wavelength to 700 nm. Zero the instrument with distilled waterin the sample cell and in the reference beam. Fill the sample cell withblank solution and read against distilled water. Note this value andsubtract from each sample value. In normal practice, the absorbancesfalls between 0.02 and 0.8 absorbance units.

Calculations (using the standard amylose):

Plot a curve using g/100 ml of standard concentrations as the x axisversus the absorbance @700 nm as the y axis.

${\%\mspace{14mu}{Amylose}} = {\frac{\begin{matrix}\left( {{Amylose}\mspace{14mu}{g/100}\mspace{14mu}{ml}} \right) \\{\left( {100 - {\%\mspace{14mu}{water}}} \right) \times \left( {{Sample}\mspace{14mu}{{wt}.}} \right)}\end{matrix}}{100} \times 100}$Percent of Broken Cells Test

The percent of broken cells in the potato flakes and the average size ofthe cells is determined by simple observation through the lightmicroscope. A small amount of flakes is spread on a portaglass, and 2–3drops of water are added immediately. After 30 sec., the sample is readyto be observed through the light microscope (×100). The % broken cellsare determined.

Hot Paste and Cold Paste Viscosities

Accurately weigh 30 g of flakes on a moisture free basis and transferquantitatively to a 600 ml beaker. Add about 400 ml of water to theflakes sample and mix thoroughly to obtain a homogeneous suspension. Thedispersion is transferred to the sample cup of an amylograph and theinstrument head is lowered into the operating position. Start theamylograph with the thermo-regulator transport switch in the neutralposition, heat off, and the cup speed at 75 rpm. Heat at a rate of 1.5°C. per min. until the sample reaches 90° C. The thermo-regulator switchis set at neutral and held at 90° C. for 10 min. This is the hot pasteviscosity. Then the thermo-regulator switch is changed to cool at 1.5°C. per minute to 50° C. This is the cold paste viscosity. (TheAmylograph Handbook, edited by William C. Shuey and Keith H. Tipples,AACC, 1994.) Hot and cold paste viscosities are measured in BrabenderUnits (BU).

Particle Size Distribution Test

-   1. Weigh dehydrated potatoes.-   2. Weigh the screens and then stack them in the following order top    to bottom: U.S. #16, #20, #40, #100 and bottom pan. Pour in the    dehydrated potatoes. Put the screens in a rotap unit. Turn on the    rotap unit for one minute.-   3. Weigh and record the total weight of potato material on the    screens.    Sheet Strength Test

The sheet strength is determined as follows: Sheet strength is themeasurement of the force needed to break a dough sheet of 0.635 mm. Thesheet strength is read as the maximum peak force (gf) of a graphobtained from force against distance. The test is designed to measurepotato dough sheet strength. All products are tested at roomtemperature. Sheet strength is an average of ten repetitions of eachtest. The sheet strength is measured by preparing a dough comprising:

-   -   a) 200 g of solids;    -   b) 90 g of water; and    -   c) 0.5 g of distilled mono and diglyceride of partially        hydrogenated soybean oil emulsifier available from Quest.

The dough is made in a small Cuisinart® mixer at low speed for 10–20seconds. After mixing the dough is sheeted using a conventional millingmachine to a thickness of 0.635 mm (22 mils). The mill rolls are usually1.2 meter length×0.75 diameter meter.

This test is conducted using a Texture Analyzer (TA-XT2) from TextureTechnologies Corp. This equipment uses a software called XTRAD. Thistest utilizes a 7/16″ diameter acrylic cylinder probe (TA-108), whichhas a smooth edge to minimize any cutting of the dough sheet. The doughsheet is held between two aluminum plates (10×10 cm). The aluminumplates have a 7 cm diameter opening in the center. Through this openingthe probe makes contact with the sheet and pushes it downwards until itbreaks. These plates have an opening in each corner to hold the sheetdough in place. Each dough sheet is pre-punched with holes to fit overthe alignment pins at the corners of the plate and cut to the size(10×10 cm) of the plate. This provides uniform tension as the probemoves down and through the sheet. The probe travels at 2 mm/second untilthe dough sheet surface is detected at 20 grams of force. The probe thentravels at 1.0 mm/second for up to 50 mm, a distance chosen to stretchthe dough sheet until it thoroughly ruptures. The probe withdraws at10.0 mm/second. The probe is run in a “Force vs Compression” mode, whichmeans the probe will move downward measuring the force.

The embodiments of the present invention are illustrated by thefollowing examples.

EXAMPLES 1–3

Examples 1–3 are prepared from (1) pre-conditioned potato slabs, (2) acombination of slabs, slivers and nubbins and (3) slivers and nubbins.The potato pieces are processed according to the method of the presentinvention. The potato mash is drum dried. The physical properties of thedehydrated flakes are measured and microscopic observations are made.The processing parameters and physical properties of the dehydratedpotato flakes are listed in Table 1 and Table 2 below.

TABLE 1 Process parameters for making dehydrated potato flakes ProcessParameters Example 1 Example 2 Example 3 % Pre-conditioned Slabs 100 600 % Slivers & nubbins 0 40 100 Cooking Pressure (PSI) 5 5 5 Cooking time(min) 19 21 23 Drum Speed (rev/sec) 10.5 10.5 10.5 Sheet Thickness (mm)0.2 0.2 0.2

TABLE 2 Physical properties of dehydrated potato flakes Flake PropertiesExample 1 Example 2 Example 3 Moisture (%) 6.0 6.0 6.0 WAI 7.9 8.6 8.1Amylose (%) 20 22.0 22.5 HPV (BU)* 290 — 320 CPV (BU) 200 — 220Microscopic 50% broken cells 50% broken cells 50% broken Observationcells * Brabender Units

EXAMPLES 4–5

The following examples compare dehydrated potato flakes preparedaccording to a conventional process conditions to dehydrated potatoflakes prepared according to the present invention. See Table 3. The rawpotato used to produce the flakes of Example 4 is fast cooked (i.e,temperature rise of about 75° F./minute until the potato slabs reach atemperature of about 180° F.). The raw potatoes used to produce thepotato flakes of Example 5 is slow cooked (i.e., temperature rise ofabout 12° F./minute until the potato slabs reach a temperature of about180° F.).

TABLE 3 Comparison of dehydrated potato flakes Process ParametersExample 4 Example 5 % Slabs 100 100 Cooking Pressure (psi) 45 10 Cookingtime (min) 50 28 Drum Speed (rev/sec) 4.5 WAI 10.3 8.5 Amylose (%) 8.422.3 HPV (BU)* 400 280 CPV (BU) 200 200

EXAMPLE 6

A dough composition is prepared from the potato flakes of the presentinvention having the physical properties listed below. The doughcomposition comprises 30% water and 70% of the following mixture ofingredients:

Ingredient Wt. % in mixture Potato flakes 78 Wheat Starch 9 Corn Meal 9Malto-dextrin 4

The physical properties of dehydrated potato flakes used are shown inthe following table:

Flake Properties Example Moisture (%) 6.0 WAI 8.5 Amylose (%) 24 HPV(BU)* 200 CPV (BU) 200 Microscopic Observation 50% broken cells*Brabender Units

The potato flakes, wheat starch and corn meal are blended in aTurbulizer® mixer. The maltodextrin is dissolved in the water and addedto the blend. The blend is mixed to form a loose, dry dough.

The dough is sheeted by continuously feeding it through a pair ofsheeting rolls forming an elastic continuous sheet without pin holes.Sheet thickness is controlled to 0.02 inches (0.05 cm). The dough sheetstrength is 211 gram force.

The dough sheet is then cut into oval shaped pieces and fried in aconstrained frying mold at 375° F. for about 12 seconds. The frying oilis a blend of cottonseed and corn oils. The fried pieces contain about38% fat.

EXAMPLE 7

A dough is prepared from the following ingredients:

Ingredient Wt. % of total formula Potato flakes (same as in example 1)53.10 Potato granules 5.90 Maltodextrin 4.50 Water 32.70 *Emulsifier3.00 Sugar 0.40 Salt 0.40

The maltodextrin is mixed with water to make a syrup. The syrup is addedto the remaining ingredients as in Example VI to make a loose, drydough.

The dough is sheeted by continuously feeding it through a pair ofsheeting rolls forming an elastic continuous sheet without pin holes.Sheet thickness is controlled to 0.02 inches (0.05 cm). The front rollis heated to about 90° F. (32° C.) and the back roll is heated to about135° F. (57° C.). The dough sheet is then cut into oval shaped piecesand fried in a constrained frying mold at 385° F. (196° C.) in OLEAN™ (anon-digestible fat made by The Procter and Gamble Company) for about 12seconds. The product is held in the molds for about 20 seconds to allowthe OLEAN™ to drain. The resulting product has a non-digestible fatlevel of about 30%. The digestible fat level from the emulsifier is lessthan 0.25 grams/30 gram serving.

1. A mixture of dehydrated potato flakes comprising: (a) from about 40%to about 60% broken cells; (b) from about 16% to about 27% amylose;and(c) from about 5% to about 10% moisture; wherein said mixture comprisespotato flakes having a particle size distribution such that: (1) from60% to about 70% remain on a #100 U.S. screen; (2) from 20% to about 40%remain on a #40 U.S. screen; (3) from about 1% to about 3% remain on a#20 U.S. screen; and (4) from 1% to about 3% remain on a #16 U.S.screen.
 2. Dehydrated potato flakes according to claim 1 wherein saidflakes comprise from about 45% to about 50% broken cells; from about 20%to about 27% amylose; and from about 7% to about 8% moisture. 3.Dehydrated potato flakes according to claim 1 wherein said flakes have awater absorption index of from about 6.7 to about 9.5 grams of water pergram of flakes.
 4. Dehydrated potato flakes according to claim 1 havinga hot paste viscosity of from about 100 BU to about 320 BU. 5.Dehydrated potato flakes according to claim 4 having a hot pasteviscosity of from about 240 BU to about 300 BU.
 6. Dehydrated potatoflakes according to claim 4 having a cold paste viscosity of from about100 BU to about 230 BU.
 7. Dehydrated potato flakes according to claim 6having a hot paste viscosity of from about 240 BU to about 300 BU. 8.Dehydrated potato flakes according to claim 7 having a cold pasteviscosity of from about 120 BU to about 220 BU.
 9. Dehydrated potatoflakes according to claim 6 having a hot paste viscosity of from about275 BU to about 290 BU and a cold paste viscosity of from about 150 BUto about 210 BU.
 10. Dehydrated potato flakes according to claim 6wherein said flakes are prepared from raw potatoes.
 11. Dehydratedpotato flakes according to claim 1 wherein said flakes comprise fromabout 17% to about 20% amylose; and wherein said flakes are producedfrom pre-conditioned potato pieces.
 12. Dehydrated potato flakesaccording to claim 11 having a water absorption index of from about 7grams to about 9 grams of water per gram of flakes.
 13. Dehydratedpotato flakes according to claim 12 having a hot paste viscosity of fromabout 100 BU to about 280 BU.
 14. Dehydrated potato flakes according toclaim 13 having a hot paste viscosity is from about 150 BU to about 250BU.
 15. Dehydrated potato flakes according to claim 12 having a coldpaste viscosity of from about 100 BU to about 200 BU.
 16. Dehydratedpotato flakes according to claim 15 having cold paste viscosity is fromabout 120 BU to about 180 BU.
 17. Dehydrated potato flakes according toclaim 12 having a hot paste viscosity of from about 190 BU to about 230BU and a cold paste viscosity of from about 140 BU to about 160 BU. 18.Dehydrated potato flakes according to claim 17 wherein saidpre-conditioned pieces are selected from the group consisting of potatoslabs, potato nubbins, potato slivers and mixtures thereof. 19.Dehydrated potato flakes according to claim 1 prepared from 100% sliversand nubbins wherein said potato flakes comprise from about 16% to about20% amylose.
 20. Dehydrated potato flakes according to claim 19 whereinsaid flakes have a water absorption index of from about 6.7 to about 8.3grams of water per gram of flakes, a hot paste viscosity of from about100 BU to about 280 BU and a cold paste viscosity from about 120 BU toabout 200 BU.
 21. Dehydrated potato flakes according to claim 20 whereinsaid flakes are prepared from pre-conditioned potato pieces.